The backlight module is an important component for a display device and light-outgoing performance of the backlight module may directly affect display effect of the display device.
The collimated light such as laser can be applied to the backlight module of the display device for enhancing the display effect of the display device, e.g., enhancing color gamut. The laser has high directionality and high color purity, so the range of the color gamut of the display device can be greatly enlarged by applying the laser to the backlight for a liquid crystal screen. Current laser display can have more than 120% national television standards committee (NTSC) color gamut and good color expression. In a backlight module in related technology, multiple independent light sources are arranged at one side of a light guide plate and the light sources are spaced from each other. In the case that each light source is a collimated light source emitting the laser and the laser is not subjected to light-mixing, light entering the light guide plate of the backlight module is not uniform and the display effect may be affected. In addition, due to directionality and complexity in light mixing of the laser, a light-mixing device for laser is complicated and thus the backlight is heavy and expensive.